A THREE-YEAR-OLD boy is dead and his father is in police custody after a stabbing in suburban Adelaide.

Police said the boy suffered numerous stab wounds and, despite frantic efforts by ambulance crews and medical staff at Adelaide Women's and Children's Hospital, he died from his injuries.

Emergency crews were responding to an accident on Gorge Road, at the intersection of Hockley Terrace at Athelstone, about 9am when another car with the injured boy flagged down police, The Advertiser reported.

South Australian Police confirmed they were approached by a man who said he had injured his son.

They haven't established where the man was heading to and where the boy was injured.